A voice recorder is one of devices for recoding speech. The voice recorder continuously records sounds around a microphone as voice on a recording operation. Thus recorded data is used subsequently to hear a playback of a recording as it is. A user is required to instruct the voice recorder to start and to stop the recording by a button operation.
On the other hand, speech recognition techniques for recognizing input speech of a microphone and converting into text data are widely used. For the speech recognition techniques, there are an isolated word recognition technique and a connected speech recognition technique. Both of techniques intend to develop various services by checking input speech data using a speech recognition dictionary which is preliminarily created, and automatically converting into a text having the highest likelihood.
Generally, for on/off control of speech recognition, a press-to-talk method and a push-to-talk method are used. In the press-to-talk method, a button for on/off control is required to be pressed down during speech input. In the push-to-talk method, only starting of speech input is instructed by pushing down a button for on/off control, and stopping of the speech input is automatically executed by detecting a silent interval by the speech recognition system. With either methods, on the occasion of speech input, the user must instruct the system by button operation. For the user, there are problems that the button operation is troublesome and that it is difficult to push down the button with a suitable timing until the user is accustomed.
Consequently, a method has been proposed in which, by placing the microphone other than the operation side, speech input is automatically turned on when detecting that the microphone side is turned upward at the occasion of speech act. However, when speech input is switched on and off only by the basis of the orientation of the microphone side, the microphone side is required to be turned to a different direction from the upward direction in order to stop the speech input. Also, while the microphone side is upward, the on state of the speech input continues.
Moreover, as a problem of the speech input device of a handheld type, such as a remote controller and the like, a microphone gain and a speech recognition parameter may not be suitably tuned because a distance between lips of the user and the microphone is different depending on the user. In this regard, it is thought of as one of reasons why a speech recognition accuracy using the handheld type microphone is lower as compared with a head set type microphone.